Modern aircraft currently operated by the commercial airline industry employ airborne data acquisition (ADA) equipment, such as a digital flight data acquisition unit (DFDAU) as a non-limiting example, which monitor signals supplied from a variety of transducers distributed throughout the aircraft, and provide digital data representative of the aircraft's flight performance based upon such transducer inputs. As flight performance data is obtained by the acquisition equipment, it is stored in an attendant, physically robust, flight data recorder (commonly known as the aircraft's "black box"), so that in the unlikely event of an in-flight mishap, the flight data recorder can be removed and the stored flight performance data analyzed to determine the cause of the anomaly.
In a further effort to improve aircraft safety, rather than wait for an accident to happen before analyzing flight recorder data, the Federal Aviation Administration (FAA) has issued a draft advisory circular AC-120-XX, dated Sep. 20, 1995, entitled "Flight Operational Quality Assurance Program" (FOQA), which recommends that the airlines look at the information provided by the digital flight data acquisition unit at regular intervals.
One suggested response to this recommendation is to equip each aircraft with a redundant flight data recording unit having a removable data storage medium, such as a floppy disc. Such an auxiliary digital data recorder is intended to allow aircraft safety personnel to gain access to the flight performance data by physically removing the auxiliary unit's data disc, the contents of which can then be input to an aircraft performance analysis data processing system for evaluation.
Although installing such a redundant flight data recording unit allows airline personnel to retrieve a copy of the flight performance data for subsequent evaluation, when considering the large volume of aircraft traffic experienced by major commercial airports, the above-proposed scheme is not only extremely time and manpower intensive, but is prone to substantial misidentification and aircraft/data association errors.
Other proposals, described in U.S. Pat. No. 5,359,446, are to use either a direct line-of-sight infrared link or a fiber optic cable to couple an on-board aircraft computer system with a ground-based computer system. Obvious drawbacks to these systems are the fact that not only do they employ complex and expensive components, but require that the aircraft be parked at the gate, so that the line-of-sight infrared transceivers or the fiber optic connection assemblies can be properly interlinked. As a consequence, neither of these types of systems is effective for use with commuter, cargo or military aircraft, which are customarily parked on an apron, rather than at a mating jetway, where such an optical link is to be provided.